Confirmation of the identify of Biomphalaria glabrata--derived "minicytes" (schistosome sporocyst-attacking cells) is to be attempted by karyotype analysis and serological procedures (immunoelectrophoresis). The in vivo role of these cells in snail responses to schistosome penetration will be studied. Cells will be radioactively labelled in vitro, then introduced into snails just prior to snail exposure to schistosome miracidia. Tissue sections will be studied by autoradiography. Classical cell culture procedures will continue to be used in present and future efforts to establish a cell line from these cells. Early passages will be frozen for storage in liquid nitrogen. Experiments will be run in which the influence of snail plasma will be determined with respect to the sporocyst-killing activities of the cells.